Convert MOBI to AZW3.
Upgrade a DRM-free MOBI ebook to AZW3, the newer Kindle KF8 format, for modern Kindles loaded over USB.
MOBI is the legacy format
Amazon has retired MOBI in its own pipeline. Converting older files to AZW3 keeps a personal library in the format current Kindles use natively.
Sideload it
Copy the AZW3 to the Kindle's documents folder over USB and it shows up in the library.
Or go to EPUB
For Send to Kindle or a non-Kindle reader, MOBI to EPUB is the better conversion.
How it works
- 01
Upload your MOBI
Drop a file or pick one from your device. Private by default.
- 02
Convert with Calibre
Calibre rebuilds the book as a Kindle KF8 (AZW3) file.
- 03
Download
Grab your AZW3.
Modern Kindle format
Chapters and table of contents kept
Private uploads, auto-deleted after 1 hour
No watermark, no signup to try
Open-source Calibre engine
MOBI to AZW3
This re-flows the book into AZW3, carrying chapters, the table of contents and images. Reflowable ebook formats adapt to the reader's screen and font size. Heavy fixed layouts (comics, textbooks) convert less cleanly.
Common questions
Is it free?+
Yes. Convert MOBI to AZW3 free. No signup and no watermark. Free covers 10 server conversions a day, up to 100 MB a file. Pro removes the daily limit and raises the file limit to 2 GB.
Is my file private?+
Your file is uploaded to a private bucket, converted on our own engine, and auto-deleted after 1 hour. It is never sent to a third-party converter.
Will the book look better?+
AZW3 supports richer formatting than MOBI, but the converter can only work with what the MOBI contains. The main gain is a cleaner, current file that modern Kindles handle well.
Does it work on protected books?+
No. Only DRM-free MOBI files can be converted.
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